1. Field of the Invention
The present invention relates generally to a magnetic recording and reproducing apparatus in which digitized picture signals and digitized information signals are recorded on a magnetic tape through a rotational head while forming a series of inclined video tracks on the magnetic tape and are reproduced from the tracks of the magnetic tape, and more particularly to a magnetic recording and reproducing apparatus in which any of groups of digitized signals transmitted at different data rates is recorded and reproduced.
2. Description of the Related Art
As a magnetic recording and reproducing apparatus in which digitized signals are recorded and reproduced in/from a magnetic recording medium such as a magnetic tape through a rotational head, a video tape recorder, a digital tape recorder or the like are conventionally known. In the above conventional apparatus, picture signals and audio signals converted into digital signals are recorded at a high recording density and are reproduced.
However, digital signals are recorded and reproduced at a fixed recording data rate in the conventional magnetic recording and reproducing apparatus. Therefore, in cases where digital signals transmitted at a data rate lower than the fixed recording data rate are recorded in the conventional apparatus, a remaining data region between data regions for the digital signals is filled with zero data xe2x80x9c0xe2x80x9d to change the digital signals to processed digital signals having the fixed recording data rate, and the processed digital signals are recorded and reproduced at the fixed recording data rate in the conventional apparatus. Therefore, even though the digital signals transmitted at the data rate lower than the fixed recording data rate are input to the conventional apparatus, an allowable recording time in the conventional apparatus for digital signals transmitted at a data rate lower than the fixed recording data rate cannot be lengthened. In other words, there is a drawback that a recording capacity for the digital signals transmitted at the data rate lower than the fixed recording data rate is lower than that for the digital signals transmitted at the fixed recording data rate.
2.1. Previously Proposed Art:
To solve the above drawback, For example, the digital signals are modulated to PCM signals according to a pulse code modulation (PCM), and the PCM signals are recorded and reproduced through a rotational head in a PCM signal recording and reproducing apparatus (the Published Unexamined Japanese Patent Application No.S59-195306 (195306/1984)). Also, an audio digital tape recorder operated with a rotational head is proposed (the Published Unexamined Japanese Patent Application No.S61-139906 (139906/1986)).
In the Application No.S61-139906, the audio digital tape recorder has a rotational cylinder on which a magnetic tape is wound, a pair of rotational heads which are attached to the rotational cylinder and have different azimuth angles, and a tape driving means for driving the magnetic tape at a prescribed speed. In the above configuration, the magnetic tape travels at a first tape traveling speed by the function of the tape driving means in cases where digital signals transmitted at a standard data rate are input. Also, the magnetic tape travels at a second tape traveling speed equal to ⅓ the first tape traveling speed by the function of the tape driving means in cases where digital signals transmitted at a low data rate equal to ⅓ the standard data rate are input, and the digital signals are recorded or reproduced each time one of the rotational heads traces the magnetic tape three times. Therefore, regardless of whether digital signals transmitted at the standard data rate or at the low data rate are input to the audio digital tape recorder, the digital signals can be recorded and reproduced at the same data rate.
2.2. Problems to be Solved by the Invention:
However, the data rate in the above audio digital tape recorder is limited to the standard data rate and the low data rate (⅓ standard data rate) because of the relationship between the different azimuth angles in a recording operation, and a digital data recording and reproducing apparatus in which picture signals, audio signals and other information signals in a moving picture experts group 1 (MPEG1), a moving picture experts group 2 (MPEG2), a digital video broadcasting (DVD), an advanced television (ATV) and the like are converted into digital signals transmitted at various data rates and the digital signals are efficiently recorded and reproduced has been recently required. Therefore, digital signals cannot be efficiently recorded or reproduced in cases where the digital signals transmitted at one of other data rates are input, and there is a drawback that a utilization efficiency of a recording medium for digital signals cannot be enhanced.
That is, in cases where a recording and reproducing technique in the above audio digital tape recorder is simply extended to be applied for digital signals transmitted at an arbitrary data rate equal to 1/(2N) (N is an integer) the standard data rate, a pair of video tracks adjacent to each other on the magnetic tape have the same azimuth, and there is a drawback that a guard bandless azimuth recording cannot be performed in the above audio digital tape recorder.
Also, in cases where the rotational speed of the rotational cylinder is changed to read out digital signals recorded at a fixed data rate, even though the digital signals are recorded on the magnetic tape in equal magnetic inversion intervals, the inversion frequency of the digital signals reproduced changes according to the rotational speed of the rotational cylinder. Therefore, it is required to prepare a waveform equalization circuit for each rotational speed of the rotational cylinder, and there is a drawback that the configuration of the above audio digital tape recorder is complicated.
Also, in the PCM signal recording and reproducing apparatus disclosed in the Application No.S59-195306, the PCM signals time-compressed are recorded and reproduced in an attaching period in which the rotational head is attached to the magnetic tape. In this case, it is required to stop the driving of the magnetic tape three times in the attaching period each time the rotational head is rotated at a prescribed rotational speed, and it is required to move the magnetic tape at a high speed during the traveling of the magnetic tape. Therefore, there is a drawback that the control of the magnetic tape is complicated.
A first object of the present invention is to provide, with due consideration to the drawbacks of such a conventional magnetic recording and reproducing apparatus, a magnetic recording and reproducing apparatus in which digital signals are efficiently recorded in a magnetic recording medium regardless of a data rate of the digital signals and digital signals recorded at any of various data rates are reproduced without complicating the configuration of a reproducing circuit.
A second object of the present invention is to provide a magnetic recording and reproducing apparatus in which digital signals transmitted at a first data rate or at an arbitrary data rate equal to 1/N the first data rate are recorded and reproduced without changing the rotational speed of a rotational cylinder in a reproducing operation according to the data rate of the recorded digital signals and without using any additional rotational head.
The first object is achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate, a second data rate equal to 1/N (N is a natural number) the first data rate or a third data rate equal to N times the first data rate and producing a plurality of blocks of digital recording signals; control means for generating an information signal which indicates a first traveling speed of a magnetic recording medium in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means, a second traveling speed equal to 1/N the first traveling speed in cases where the input digital signals transmitted at the second data rate are processed in the signal processing means or a third traveling speed equal to N times the first traveling speed in cases where the input digital signals transmitted at the third data rate are processed in the signal processing means;
driving means for driving the magnetic recording medium at the first, second or third traveling speed according to the information signal generated in the control means;
recording and reading means, having a first azimuth head of a first azimuth angle and a second azimuth head of a second azimuth angle, for recording the blocks of digital recording signals processed in the signal processing means and the information signal generated in the control means on the magnetic recording medium driven by the driving means to form alternate rows of first blocks of digital recording signals recorded through the first azimuth head and second blocks of digital recording signals recorded through the second azimuth head on the magnetic recording medium and reading the blocks of digital recording signals and the information signal recorded on the magnetic recording medium on condition that the first blocks of digital recording signals are read through the first azimuth head and the second blocks of digital recording signals are read through the second azimuth head; head tracing means for repeatedly making the first and second
azimuth heads of the recording and reading means trace the magnetic recording medium at a fixed cycle, the first blocks of digital recording signals being recorded or read through the first azimuth head each time the first azimuth head traces the magnetic recording medium at the fixed cycle, and the second blocks of digital recording signals being recorded or read through the second azimuth head each time the second azimuth head traces the magnetic recording medium at the fixed cycle; and
signal reproducing means for reproducing the information signal read through the recording and reading means, transferring the information signal to the driving means to drive the magnetic recording medium at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals, and reproducing the blocks of digital recording signals read through the first and second azimuth heads.
In the above configuration, in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means in a recording operation, an information signal indicating a first traveling speed of a magnetic recording medium is generated in the control means, and the magnetic recording medium is driven at the first traveling speed by the driving means according to the information signal.
In cases where the input digital signals transmitted at the second data rate are processed in the signal processing means in a recording operation, an information signal indicating a second traveling speed is generated in the control means, and the magnetic recording medium is driven at the second traveling speed by the driving means according to the information signal. In this case, a ratio of the first data rate to the second data rate is equal to another ratio of the first traveling speed to the second traveling speed.
In cases where the input digital signals transmitted at the third data rate are processed in the signal processing means in a recording operation, an information signal indicating a third traveling speed is generated in the control means, and the magnetic recording medium is driven at the third traveling speed by the driving means according to the information signal. In this case, a ratio of the first data rate to the third data rate is equal to another ratio of the first traveling speed to the third traveling speed.
Thereafter, the digital recording signals are recorded on the magnetic recording medium with the information signal while the first and second azimuth heads of the recording and reading means repeatedly tracing the magnetic recording medium at a fixed cycle. In this case, alternate rows of first blocks of digital recording signals recorded through the first azimuth head and second blocks of digital recording signals recorded through the second azimuth head are formed on the magnetic recording medium.
Accordingly, the input digital signals can be efficiently and reliably recorded on the magnetic regardless of the data rate of the input digital signals.
Also, because the traveling speed of the magnetic recording medium is controlled in proportion to the data rate of the input digital signals and the first and second azimuth heads trace the magnetic recording medium at the fixed cycle regardless of the data rate of the input digital signals, the digital recording signals can be recorded on the magnetic recording medium at a constant data recording density regardless of the data rate of the input digital signals. Therefore, a data recording time of the magnetic recording medium can be prolonged N times for the input digital signals transmitted at the second data rate as compared with that for the input digital signals transmitted at the first data rate.
Thereafter, in a reproducing operation, the information signal recorded on the magnetic recording medium is read out from the magnetic recording medium to the signal reproducing means through the recording and reading means and is transferred to the driving means. Therefore, the magnetic recording medium is driven at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals. Thereafter, the blocks of digital recording signals recorded are read out from the magnetic recording medium through the first and second azimuth heads of the recording and reading means which trace the magnetic recording medium at the fixed cycle. In this case, the first blocks of digital recording signals are read out through the first azimuth head, and the second blocks of digital recording signals are read out through the second azimuth head. Thereafter, the blocks of digital recording signals are reproduced in the signal reproducing means.
Accordingly, because the tracing cycle of the first and second azimuth heads in the reproducing operation is the same as that in the recording operation and the magnetic recording medium is driven in the reproducing operation at the same traveling speed as that in the recording operation, digital reproducing signals which are the same as the digital recording signals can be obtained in the signal reproducing means. In other words, reproducibility of the input digital signals is superior in the magnetic recording and reproducing apparatus.
Also, because the tracing cycle of the first and second azimuth heads is fixed regardless of the recording or reproducing operation and regardless of the data rate of the input digital signals and the magnetic recording medium is driven in the reproducing operation at the same traveling speed as that in the recording operation, the configuration of the magnetic recording and reproducing apparatus can be simplified.
The first object is also achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate, a second data rate equal to 1/(2*N) (N is a natural number) the first data rate or a third data rate equal to 1/(2*N+1) the first data rate and producing a plurality of blocks of digital recording signals;
control means for generating an information signal which indicates a first traveling speed of a magnetic recording medium in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means, a second traveling speed equal to 1/(2*N) the first traveling speed in cases where the input digital signals transmitted at the second data rate are processed in the signal processing means or a third traveling speed equal to 1/(2*N+1) the first traveling speed in cases where the input digital signals transmitted at the third data rate are processed in the signal processing means;
driving means for driving the magnetic recording medium at the first, second or third traveling speed according to the information signal generated in the control means; recording and reading means, having a first azimuth head of a
first azimuth angle and a second azimuth head of a second azimuth angle, for recording the blocks of digital recording signals processed in the signal processing means and the information signal generated in the control means on the magnetic recording medium driven by the driving means to form alternate rows of first blocks of digital recording signals recorded through the first azimuth head and second blocks of digital recording signals recorded through the second azimuth head on the magnetic recording medium and reading the blocks of digital recording signals and the information signal recorded on the magnetic recording medium on condition that the first blocks of digital recording signals are read through the first azimuth head and the second blocks of digital recording signals are read through the second azimuth head;
a rotational drum, on which the first and second azimuth heads of the recording and reading means are attached, for circulating the first and second azimuth heads at a fixed rotational speed to repeatedly make the first and second azimuth heads trace the magnetic recording medium at a fixed cycle, the first blocks of digital recording signals being recorded or read through the first azimuth head each time the first azimuth head traces the magnetic recording medium at the fixed cycle, and the second blocks of digital recording signals being recorded or read through the second azimuth head each time the second azimuth head traces the magnetic recording medium at the fixed cycle; and
signal reproducing means for reproducing the information signal read through the recording and reading means, transferring the information signal to the driving means to drive the magnetic recording medium at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals, and reproducing the blocks of digital recording signals read through the first and second azimuth heads.
In the above configuration, the magnetic recording medium is driven at the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means, the magnetic recording medium is driven at 1/(2N) the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at 1/(2N) the first data rate are processed in the signal processing means, and the magnetic recording medium is driven at 1/(2N+1) the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at 1/(2N+1) the first data rate are processed in the signal processing means. Therefore, regardless of the data rate of the input digital signals, the digital recording signals can be reliably recorded on the magnetic recording medium at a constant data recording density.
Also, when the digital recording signals recorded in the magnetic recording medium are reproduced, the magnetic recording medium is driven by the driving means at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals. Therefore, regardless of the data rate of the input digital signals, the digital recording signals recorded in the magnetic recording medium can be reliably reproduced at a high reproducibility, and the configuration of the magnetic recording and reproducing apparatus can be simplified.
The first object is also achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate or a second data rate equal to 1/N (N is a natural number) the first data rate and producing a plurality of blocks of digital recording signals;
control means for generating an information signal which indicates a first traveling speed of a magnetic recording medium in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means or a second traveling speed equal to 1/N the first traveling speed in cases where the input digital signals transmitted at the second data rate are processed in the signal processing means;
driving means for driving the magnetic recording medium at the first or second traveling speed according to the information signal generated in the control means;
recording and reading means, having a first head of a first azimuth angle and a second head of a second azimuth angle, for recording the blocks of digital recording signals processed in the signal processing means and the information signal generated in the control means on the magnetic recording medium driven by the driving means to form alternate rows of first blocks of digital recording signals recorded through the first head and second blocks of digital recording signals recorded through the second head on the magnetic recording medium and reading the blocks of digital recording signals and the information signal recorded on the magnetic recording medium on condition that the first blocks of digital recording signals are read through the first head and the second blocks of digital recording signals are read through the second head;
a rotational drum, on which the first and second heads of the recording and reading means are attached, for circulating the first and second heads at a fixed rotational speed to repeatedly make the first and second heads trace the magnetic recording medium at a fixed cycle, the first blocks of digital recording signals being recorded or read through the first head each time the first head traces the magnetic recording medium at the fixed cycle, and the second blocks of digital recording signals being recorded or read through the second head each time the second head traces the magnetic recording medium at the fixed cycle; and
signal reproducing means for reproducing the information signal read through the recording and reading means, transferring the information signal to the driving means to drive the magnetic recording medium at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals, and reproducing the blocks of digital recording signals read through the first and second heads.
In the above configuration, the magnetic recording medium is driven at the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means, and the magnetic recording medium is driven at 1/N the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at 1/N the first data rate are processed in the signal processing means. Therefore, regardless of the data rate of the input digital signals, the digital recording signals can be reliably recorded on the magnetic recording medium at a constant data recording density.
Also, when the digital recording signals recorded in the magnetic recording medium are reproduced, the magnetic recording medium is driven by the driving means at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals. Therefore, regardless of the data rate of the input digital signals, the digital recording signals recorded in the magnetic recording medium can be reliably reproduced at a high reproducibility, and the configuration of the magnetic recording and reproducing apparatus can be simplified.
The first object is also achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate or a second data rate equal to N times (N is a natural number) the first data rate and producing a plurality of blocks of digital recording signals;
control means for generating an information signal which indicates a first traveling speed of a magnetic recording medium in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means or a second traveling speed equal to N times the first traveling speed in cases where the input digital signals transmitted at the second data rate are processed in the signal processing means;
driving means for driving the magnetic recording medium at the first or second traveling speed according to the information signal generated in the control means;
recording and reading means, having a first azimuth head of a first azimuth angle and a second azimuth head of a second azimuth angle, for recording the blocks of digital recording signals processed in the signal processing means and the information signal generated in the control means on the magnetic recording medium driven by the driving means to form alternate rows of first blocks of digital recording signals recorded through the first azimuth head and second blocks of digital recording signals recorded through the second azimuth head on the magnetic recording medium and reading the blocks of digital recording signals and the information signal recorded on the magnetic recording medium on condition that the first blocks of digital recording signals are read through the first azimuth head and the second blocks of digital recording signals are read through the second azimuth head;
a rotational drum, on which the first and second azimuth heads of the recording and reading means are attached, for circulating the first and second azimuth heads at a fixed rotational speed to repeatedly make the first and second azimuth heads trace the magnetic recording medium at a fixed cycle, the first blocks of digital recording signals being recorded or read through the first azimuth head each time the first azimuth head traces the magnetic recording medium at the fixed cycle, and the second blocks of digital recording signals being recorded or read through the second azimuth head each time the second azimuth head traces the magnetic recording medium at the fixed cycle; and
signal reproducing means for reproducing the information signal read through the recording and reading means, transferring the information signal to the driving means to drive the magnetic recording medium at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals, and reproducing the blocks of digital recording signals read through the first and second azimuth heads.
In the above configuration, the magnetic recording medium is driven at the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at the first data rate are processed in the signal processing means, and the magnetic recording medium is driven at N times the first traveling speed by the driving means under the control of the control means in cases where the input digital signals transmitted at N times the first data rate are processed in the signal processing means. Therefore, regardless of the data rate of the input digital signals, the digital recording signals can be reliably recorded on the magnetic recording medium at a constant data recording density.
Also, when the digital recording signals recorded in the magnetic recording medium are reproduced, the magnetic recording medium is driven by the driving means at the same traveling speed as that at which the magnetic recording medium is driven to record the digital recording signals. Therefore, regardless of the data rate of the input digital signals, the digital recording signals recorded in the magnetic recording medium can be reliably reproduced at a high reproducibility, and the configuration of the magnetic recording and reproducing apparatus can be simplified.
The second object is achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate or a second data rate equal to 1/N (N is a natural number) the first data rate and producing a plurality of blocks of digital recording signals, a piece of data rate information which indicates a data rate of the input digital signals being included in the input digital signals;
data rate detecting means for detecting the data rate information included in the input digital signals; driving means for driving the magnetic recording medium in a traveling direction;
rotating means for rotating a rotational cylinder in a rotational direction inclined with respect to the traveling direction of the magnetic recording medium driven by the driving means;
a first head of a first azimuth angle and a second head of a second azimuth angle arranged on the rotational cylinder on condition that the first head is placed at 180 degrees apart from the second head, for alternately tracing the magnetic recording medium driven by the driving means by rotating the rotational cylinder by use of the rotating means, recording the blocks of digital recording signals and the data rate information processed in the signal processing means on the magnetic recording medium while alternately forming first azimuth tracks generated by recording first blocks of digital recording signals through the first head and second azimuth tracks generated by recording second blocks of digital recording signals through the second head on the magnetic recording medium in a track recording direction and reading the blocks of digital recording signals and the data rate information from the magnetic recording medium driven by the driving means in a track reading direction by rotating the rotational cylinder by use of the rotating means on condition that the first blocks of digital recording signals are read through the first head and the second blocks of digital recording signals are read through the second head;
signal reproducing means for reproducing the data rate information and the blocks of digital recording signals read from the magnetic recording medium through the first and second heads;
tape traveling speed control means for controlling the driving means to drive the magnetic recording medium at a first traveling speed in cases where the data rate information detected in the data rate detecting means indicates the first data rate and to drive the magnetic recording medium at a second traveling speed equal to 1/N the first traveling speed in cases where the data rate information detected in the data rate detecting means indicates the second data rate and controlling the driving means to drive the magnetic recording medium at the first traveling speed in cases where the data rate information reproduced in the signal reproducing means indicates the first data rate and to drive the magnetic recording medium at the second traveling speed in cases where the data rate information reproduced in the signal reproducing means indicates the second data rate; and
rotational cylinder control means for controlling the rotating means to rotate the rotational cylinder at a first rotational speed in cases where the data rate information detected in the data rate detecting means indicates the first data rate and to rotate the rotational cylinder at a second rotational speed equal to 1/N the first rotational speed in cases where the data rate information detected in the data rate detecting means indicates the second data rate and controlling the rotating means to rotate the rotational cylinder at the first rotational speed in cases where the blocks of digital recording signals recorded on the magnetic recording medium are read through the first and second heads.
In the above configuration, in cases where a plurality of input digital signals transmitted at a first data rate is processed in the signal processing means to generate a plurality of blocks of digital recording signals, a piece of data rate information included in the signals is detected in the data rate detecting means, and the data rate detecting means informs the tape traveling speed control means and the rotational cylinder control means of the first data rate. Thereafter, a magnetic recording medium is driven at a first traveling speed in a traveling direction by the driving means under control of the tape traveling speed control means, and a rotational cylinder is rotated at a first rotational speed by the rotating means under control of the rotational cylinder control means. Therefore, the first and second heads arranged opposite to each other on the rotational cylinder alternately trace the magnetic recording medium, and the blocks of digital recording signals including the data rate information processed in the signal processing means are recorded on the magnetic recording medium. In this case, each block of digital recording signals is, for example, provided to the first or second head for each half rotation of the rotational cylinder and is recorded. Also, first azimuth tracks generated by recording first blocks of digital recording signals through the first head and second azimuth tracks generated by recording second blocks of digital recording signals through the second head are alternately formed on the magnetic recording medium. In this case, each of the tracks is extended in a track recording direction which is inclined with respect to the traveling direction of the magnetic recording medium at a track inclination angle.
In contrast, in cases where a plurality of input digital signals transmitted at a second data rate equal to 1/N the first data rate is processed in the signal processing means, the magnetic recording medium is driven at a second traveling speed equal to 1/N the first traveling speed, and the rotational cylinder is rotated at a second rotational speed of 1/N the first rotational speed. Therefore, the blocks of digital recording signals including the data rate information processed in the signal processing means are recorded on the magnetic recording medium. In this case, each block of digital recording signals is, for example, provided to the first or second head for each rotational period of N/2 rotations of the rotational cylinder and is recorded. Also, because a second speed ratio of the second traveling speed to the second rotational speed is equal to a first speed ratio of the first traveling speed to the first rotational speed, first azimuth tracks and second azimuth tracks of which arranging conditions are the same as those in case of the first data rate are formed on the magnetic recording medium in the same manner. That is, each of the first and second azimuth tracks is extended in the same track recording direction. In addition, because each block of digital recording signals is recorded on a first or second azimuth track having a fixed track length regardless of the data rate of the input digital signals, a minimum inversion interval of magnetic charges formed on the magnetic recording medium becomes constant regardless of the data rate of the input digital signals.
Thereafter, in cases where the blocks of digital recording signals including the data rate information recorded on the magnetic recording medium are read out from the magnetic recording medium, the data rate information are reproduced in the signal reproducing means and is detected in the data rate detecting means. In cases where the data rate information which is included in the input digital signals transmitted at the first data rate is detected, the data rate detecting means informs the tape traveling speed control means of the first data rate, and the magnetic recording medium is driven at the first traveling speed in the traveling direction in the same manner. Also, in cases where the data rate information which is included in the input digital signals transmitted at the second data rate is detected, the data rate detecting means informs the tape traveling speed control means of the second data rate, and the magnetic recording medium is driven at the second traveling speed in the traveling direction in the same manner. In this case, the rotational cylinder is rotated at the first rotational speed regardless of the data rate indicated by the data rate information.
Therefore, in cases where the magnetic recording medium is rotated at the first traveling speed, the first and second heads alternately trace the first and second azimuth tracks in a track reading direction which is the same as the track recording direction, and the blocks of digital recording signals are read from the magnetic recording medium on condition that the first blocks of digital recording signals are read through the first head and the second blocks of digital recording signals are read through the second head. In this case, an inversion cycle of the blocks of digital recording signals read is determined according to the minimum inversion interval of the magnetic charges. Thereafter, the blocks of digital recording signals are reproduced in the signal reproducing means at the inversion cycle of signals.
In contrast, in cases where the magnetic recording medium is rotated at the second traveling speed, because the rotational cylinder is not rotated at the second rotational speed but rotated at the first rotational speed, each of the first azimuth tracks is traced N times by the first head in a track reading direction differing from the track recording direction, and each of the second azimuth tracks is traced N times by the second head in the track reading direction. Therefore, each block of digital recording signals is read from the magnetic tape in N tracing operations of the first or second head. In this case, because the rotational cylinder is rotated at the first rotational speed in the same manner as in the first data rate, an inversion cycle of the blocks of digital recording signals read through the first and second heads is the same as that in the first data rate. Thereafter, each block of digital recording signals read in the N tracing operations are reproduced in the signal reproducing means at the same inversion cycle of signals.
Accordingly, even though the input digital signals transmitted at the first data rate or the second data rate are input, because the rotational speed of the rotational cylinder and the traveling speed of the magnetic recording medium are changed in the same manner according to the data rate of the input digital signals, the tracks can be formed on the magnetic recording medium in equal intervals regardless of the data rate of the input digital signals without any additional third head.
Also, because the blocks of digital recording signals are alternately provided to the first and second heads having different azimuth angles to form a series of tracks on the magnetic recording medium, azimuth angles of a pair of tracks adjacent to each other differ from each other. Therefore, crosstalk occurring in a pair of tracks adjacent to each other can be prevented, and the digital recording signals can be reproduced at a high quality.
Also, because the rotational speed of the rotational cylinder is fixed to the first rotational speed in a reproducing operation regardless of the data rate of the input digital signals on condition that the minimum inversion interval of the magnetic charges on the magnetic recording medium is fixed, an inversion cycle of the digital recording signals can be fixed to a prescribed value. Therefore, a plurality of waveform equalizing circuits respectively corresponding to a data rate of the input digital signals are not required in the signal reproducing means. In other words, the configuration of the signal reproducing means can be simplified.